Use for the oleo-repellent paper sizing of carboxylic perfluoropolyethers

Abstract

Use for the oleo-repellent paper sizing of carboxylic perfluoropolyethers of formula T-O—R f -T  (I) wherein T=—CF 2 —COOH or —CF 2 CF 2 —COOH and R f is a (per)fluoropolyoxyalkylene chain.

1. A method of conferring to paper oleorepellence, comprising sizing the paper in wet-end, size-press or coating applications with perfluoropolyethers, wherein said perfluoropolyethers are only selected from compounds having the following structure:
   T-O—R f -T   (I) 
 
       wherein
 T=—CF 2 —COOH or —CF 2 CF 2 —COOH, in acid or salt form; 
 R f  is a (per)fluoropolyoxyalkylene chain, having number average molecular weight in the range 500-10,000, formed of one or more repeating units, statistically distributed along the chain, selected from the group consisting of the following structures:
   (CFXO), (CF 2 CF 2 O), (CF 2 CF 2 CF 2 O), (CF 2 CF 2 CF 2 CF 2 O), (CR 4 R 5 CF 2 CF 2 O), (CF(CF 3 )CF 2 O), and (CF 2 CF(CF 3 )O), 
 
 wherein X=F, CF 3 ; R 4  and R 5 , equal to or different from each other, are selected from the group consisting of H, Cl, or perfluoroalkyl from 1 to 4 carbon atoms. 
 
     
     
       2. The method according to  claim 1 , wherein R f  is selected from
 (A) —(CF 2 CF(CF 3 )O) a (CFYO) b —
 wherein Y is F or CF 3 ; a and b are integers such that the molecular weight is within the above range; 
 a/b is between 10 and 100; 
 or the repeating units indicated in (A) can be linked as follows:
   —(CF 2 CF(CF 3 )O) a (CFYO) b —CF 2 (R′ f )CF 2 —O—(CF 2 CF(CF 3 )O) a (CFYO) b — 
 
 wherein R′ f  is a fluoroalkylene group from 1 to 4 C atoms; 
 
 (B) —(CF 2 CF 2 O) c (CF 2 O) d (CF 2 (CF 2 ) z O) h —
 wherein c, d and h are integers such that the molecular weight is within the above range, h can be equal to 0; c/d is between 0.1 and 10; h/(c+d) is between 0 and 0.05; z is 2 or 3; 
 
 (C) —(CF 2 CF(CF 3 )O) e (CF 2 CF 2 O) f (CFYO) g —
 wherein Y is F or CF 3 ; e, f, g are integers such that the molecular weight is within the above range; 
 e/(f+g) is between 0.1 and 10, f/g is between 2 and 10; 
 
 (D) —(CF 2 (CF 2 ) z O) s —
 wherein s is an integer such to give the above molecular weight, z has the already defined meaning; 
 
 (E) —(CR 4 R 5 CF 2 CF 2 O) j —
 wherein R 4  and R 5  are equal to or different from each other and selected from the group consisting of H, Cl or perfluoroalkyl, j′ being an integer such that the molecular weight is that above indicated; said units inside the fluoropolyoxyalkylene chain can be linked with each other as follows:
   —(CR 4 R 5 CF 2 CF 2 O) p′ —R′ f —O—(CF 4 R 5 CF 2 CF 2 O) q′ — 
 
 wherein R′ f  is a fluoroalkylene group; p′ and q′ are integers such that the molecular weight is that above mentioned; 
 
 (F) —(CF(CF 3 )CF 2 O) j″ —(R′ f )—O—(CF(CF 3 )CF 2 O) j″ 
 wherein j″ is an integer such as to give the above molecular weight, R′ f  is a fluoroalkylene group from 2 to 4 C atoms. 
 
 
     
     
       3. The method according to  claim 2 , wherein the perfluoropolyether has formula:
   T″-O—(CF 2 CF 2 O) m (CF 2 O) n -T″ 
 
       wherein T″=—CF 2 —COOH, and the m, n, indexes are integers, such that the number average molecular weight is in the range 500-10,000, and the m/n ratio is between 0.1 and 10. 
     
     
       4. The method according to  claim 1 , wherein the compounds of formula (I) are used in the form of salts solubilized or emulsified in water or in mixtures of water with alcohols, glycols, or ethers, wherein the alcohols are selected from isopropanol, ethanol, methanol, and t-butanol; the ether is dipropylenglycol monomethylether; the glycols are selected from ethylene glycol and propylene glycol. 
     
     
       5. The method according to  claim 2 , wherein R 4  and/or R 5  are perfluoroalkyls having 1 to 4 C atoms. 
     
     
       6. The method according to  claim 2 , wherein when R f  is —(CR 4 R 5 CF 2 CF 2 O) j′ —, then R′ f  is a fluoroalkylene group with 1 to 4 C atoms. 
     
     
       7. A method according to  claim 1 , wherein the perfluoropolyethers of formula (I) are in aqueous compositions consisting of said perfluoropolyethers and optionally a solvent, and wherein the perfluoropolyethers of formula (I) are used in the form of salts solubilized or emulsified in water or in mixtures of water with alcohols, glycols, or ethers, wherein the alcohols are selected from isopropanol, ethanol, methanol, and t-butanol; the ether is dipropylenglycol monomethylether; and the glycols are selected from ethylene glycol and propylene glycol. 
     
     
       8. The method of  claim 1 , wherein the paper sized accordingly to the method is conferred sufficient oleorepellance to satisfy satisfies one of more of the following tests: the Ralston Purina Crease Test, Oleic Acid Test, Eukanuba Test, Turpentine Test, and Fat Acid Test. 
     
     
       9. A method for conferring oleorepellence to paper comprising sizing paper using aqueous compositions consisting of:
 A) from 15 to 25% by weight of a compound of formula (I), in the form of salts, wherein the salts are obtained by neutralization of acids with bases, and wherein the compound of formula (I) has the following structure:
   T-O—R f -T  (I) 
 
 wherein
 T=—CF 2 —COOH or —CF 2 CF 2 —COOH; 
 R f  is a (per)fluoropolyoxyalkylene chain, having number average molecular weight in the range 500-10,000, formed of one or more repeating units, statistically distributed along the chain, selected from the group consisting of the following structures:
   (CFXO), (CF 2 CF 2 O), (CF 2 CF 2 CF 2 O), (CF 2 CF 2 CF 2 CF 2 O), (CR 4 R 5 CF 2 CF 2 O), (CF(CF 3 )CF 2 O), and (CF 2 CF(CF 3 )O), 
 
 wherein X=F, CF 3 ; R 4  and R 5 , equal to or different from each other, are selected from the group consisting of H, Cl, and perfluoroalkyl having from 1 to 4 carbon atoms, 
 
 
       and optionally
 B) from 1 to 5% by weight of a solvent selected from the group consisting of alcohols, glycols, and ethers; 
 C) water as complement to 100%. 
 
     
     
       10. A method according to  claim 9 , wherein the composition comprises a solvent selected from the group consisting of isopropanol, ethanol, methanol, t-butanol, dipropylenglycol monomethylether, ethylene glycol, and propylene glycol. 
     
     
       11. The method of  claim 9 , wherein the compound of formula (I) comprises salt cations selected from the group consisting of alkaline metals, ammonium, and primary, secondary or tertiary amines in protonated form. 
     
     
       12. Oleo-repellent paper obtained by treatment with the aqueous compositions of  claim 9 , containing from 0.05 to 2% by weight with respect to the dry cellulose of a compound of formula (I)
   T-O—R f -T   (I) 
 
       wherein
 T=—CF 2 —COOH or —CF 2 CF 2 —COOH; 
 R f  is a (per)fluoropolyoxyalkylene chain, having number average molecular weight in the range 500-10,000, formed of one or more repeating units, statistically distributed along the chain, selected from the group consisting of the following structures:
   (CFXO), (CF 2 CF 2 O), (CF 2 CF 2 CF 2 O), (CF 2 CF 2 CF 2 CF 2 O), (CR 4 R 5 CF 2 CF 2 O), (CF(CF 3 )CF 2 O), and (CF 2 CF(CF 3 )O), 
 
 
       wherein X=F, CF 3 ; R 4  and R 5 , equal to or different from each other, are selected from the group consisting of H, Cl, or perfluoroalkyl from 1 to 4 carbon atoms, or one of its salts.